ggplot2 is a data visualization package for the statistical programming language R. After analyzing and plotting graphs, we can add an annotation in our graph by annotate() function. This article discusses how the font size of an annotation can be changed with the annotation() function.
Syntax: annotate()
Parameters:
- geom : specify text
- x : x axis location
- y : y axis location
- label : custom textual content
- color : color of textual content
- size : size of text
- fontface : fontface of text
- angle : angle of text
By adding annotate function with only argument geom=’text’, it shows that ggplot knows that it has to add text, but it needs another parameter such as Location of text (x,y) and text data (label=text).
Approach
- Import ggplot2
- Create/Import Dataset
- Plot the data on a graph
- Add annotation() function with required parameters
Let us first create a basic plot without annotating.
Program :
# Import Package library(ggplot2)
# df dataset df <- data.frame(a=c(2,4,8),
b=c(5, 10, 15))
# plot graph plot = ggplot(df, aes(x = a, y = b)) + geom_point() + geom_line()
# output plot |
Output:
Basic Plot
Now, Let us see how annotation can be added.
Program :
# Import Package library(ggplot2)
# df dataset df <- data.frame(a=c(2,4,8),
b=c(5, 10, 15))
# plot graph plot = ggplot(df, aes(x = a, y = b)) + geom_point() + geom_line()
plot + annotate('text',
x = 6, y = 7.5,
label = 'GeeksForGeeks',
color='darkgreen')
|
Output:
label & color
To change the size of the text, use the “size” argument. In the below example, the size of GeeksForGeeks is 10 and the color is red.
Program :
# Import Package library(ggplot2)
# df dataset df <- data.frame(a=c(2,4,8),
b=c(5, 10, 15))
# plot graph plot = ggplot(df, aes(x = a, y = b)) + geom_point() + geom_line()
plot + annotate('text', x = 6, y = 7.5,
label = 'GeeksForGeeks',
color='red',
size = 10)
|
Output:
Size